#region Copyright & License Information
/*
 * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
 * This file is part of OpenRA, which is free software. It is made 
 * available to you under the terms of the GNU General Public License
 * as published by the Free Software Foundation. For more information,
 * see COPYING.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml;
using OpenRA.FileFormats;

namespace OpenRA.Graphics
{
	
	public static class ChromeProvider
	{
		struct Collection
		{
			public string src;
			public Dictionary<string, MappedImage> regions;
		}
	
		static Dictionary<string, Collection> collections;
		static Dictionary<string, Sheet> cachedSheets;
		static Dictionary<string, Dictionary<string, Sprite>> cachedSprites;

		public static void Initialize(params string[] chromeFiles)
		{
			collections = new Dictionary<string, Collection>();
			cachedSheets = new Dictionary<string, Sheet>();
			cachedSprites = new Dictionary<string, Dictionary<string, Sprite>>();

			foreach (var f in chromeFiles)
				LoadChromeSource(f);
			
			Save("foo.yaml");
		}
		
		public static void Save(string file)
		{
			var root = new List<MiniYamlNode>();
			foreach (var kv in collections)
				root.Add(new MiniYamlNode(kv.Key, SaveCollection(kv.Value)));
			
			root.WriteToFile(file);
		}
		
		static MiniYaml SaveCollection(Collection collection)
		{
			var root = new List<MiniYamlNode>();
			foreach (var kv in collection.regions)
				root.Add(new MiniYamlNode(kv.Key, kv.Value.Save(collection.src)));
			
			return new MiniYaml(collection.src, root);
		}

		static void LoadChromeSource(string filename)
		{
			XmlDocument document = new XmlDocument();
			document.Load(FileSystem.Open(filename));
			foreach (XmlElement eCollection in document.SelectNodes("/chrome/collection"))
				LoadChromeForCollection(eCollection);
		}

		static void LoadChromeForCollection(XmlElement eCollection)
		{
			string elementName = eCollection.GetAttribute("name");
			string defaultSrc = (eCollection.HasAttribute("src") ? eCollection.GetAttribute("src") : null);

			var images = eCollection.SelectNodes("./image").OfType<XmlElement>()
				.Select(e => new MappedImage(defaultSrc, e))
				.ToDictionary(s => s.Name);
			
			collections.Add(elementName, new Collection() {src = defaultSrc, regions = images});
		}

		public static Sprite GetImage(string collection, string image)
		{
			// Cached sprite
			if (cachedSprites.ContainsKey(collection) && cachedSprites[collection].ContainsKey(image))
				return cachedSprites[collection][image];

			MappedImage mi;
			try { mi = collections[collection].regions[image]; }
			catch (KeyNotFoundException)
			{
				throw new InvalidOperationException(
					"Collection `{0}` does not have an image `{1}`".F(collection, image));
			}

			// Cached sheet
			Sheet sheet;
			if (cachedSheets.ContainsKey(mi.Src))
				sheet = cachedSheets[mi.Src];
			else
			{
				sheet = new Sheet(mi.Src);
				cachedSheets.Add(mi.Src, sheet);
			}

			// Cache the sprite
			if (!cachedSprites.ContainsKey(collection))
				cachedSprites.Add(collection, new Dictionary<string, Sprite>());
			cachedSprites[collection].Add(image, mi.GetImage(sheet));

			return cachedSprites[collection][image];
		}
	}
}